Blood Pressure Medications Increase Cancer Risk

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A group of blood pressure medications called angiotensin II receptor blockers (ARBs), used by millions of people every day to treat high blood pressure and heart failure and to reduce the risk of cardiovascular events, can increase cancer risk. The meta-analysis, which saw the largest increase in cancer risk for lung cancer, was published online in Lancet Oncology.

Angiotensin II occurs naturally in the body, and it affects the cardiovascular system in several ways, one of which is to narrow the blood vessels. When this occurs, blood pressure rises. Angiotensin II also triggers the release of a hormone that raises the level of sodium and water in the body, which also can lead to high blood pressure.

The blood pressure medications angiotensin II receptor blockers block the actions of angiotensin II, which relaxes the blood vessels and in turn lowers blood pressure and makes it easier for the heart to pump and circulate blood. The ARBs approved by the Food and Drug Administration (FDA) include candesartan (Atacand), eprosartan (Teveten), irbesartan (Avapro), losartan (Cozaar), olmesartan (Benicar), telmisartan (Micardis), and valsartan (Diovan).

Cardiologists at University Hospitals Case Medical Center evaluated data from 61,950 patients from five trials, including only three of the seven ARBs currently approved by the FDA. About 85 percent of the patients in this meta-analysis received telmisartan (Micardis), while the others received losartan or candesartan.

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Compared with the control group, individuals in the ARB segment of the study had a significantly increased risk of developing a new cancer. It is not known whether other ARBs—eprosartan, irbesartan, olmesarten, and valsartan—may also be associated with a higher risk of new cancer.

Dr. Ilke Sipahi, associate director of heart failure and transplantation and assistant professor at Case Western Reserve University School of Medicine, noted that among the malignancies examined--breast, prostate, and lung—only new lung cancer was significantly higher in the patients who took the ARBs. While the risk of lung cancer was increased by 25 percent, there was no increased risk seen for breast cancer and only a “weak trend” for prostate cancer, according to an article in heartwire.

Dr. Sipahi explained that although their findings “are robust, they need to be replicated in other studies before they can be considered as definitive.” In an accompanying comment in Lancet Oncology, Dr. Steven E. Nissen of Cleveland Clinic said ARBs “are often overprescribed as a result of aggressive marketing,” and that they should be used “with greater caution.”

Given the possible increased risk of cancer, Dr. Nissen urged that these blood pressure medications, especially telmisartan, be reserved for individuals who cannot tolerate ACE inhibitors. This step “will also save money for the healthcare system since nearly all ARBs are proprietary and ACE inhibitors are generic.” Saving money and possibly reducing the risk of cancer: a win-win.

SOURCES:
Nissen SE. Lancet Oncology 2010; DOI:10.1016/S1470-2045(10)70142-X.
Sipahi I et al. Lancet Oncology 2010; DOI:10.1016/S1470-2045(10)70106-6.

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